Vane pump device

ABSTRACT

A vane pump device includes: a rotor supporting 10 vanes movable in a rotation direction; and a cam ring having an inner circumferential surface facing an outer surface of the rotor. A fluid-suction step where transits to a fluid-discharge step by changing the pump chamber capacity in response to the rotation angle, as a result of the change in the distance from the rotation center to the inner circumferential surface of the cam ring in response to the rotation angle. A starting angle, at which the distance starts increasing after a same distance segment has reached a predetermined rotation angle, has a rotation angle difference of 2.5 degrees or less with respect to a center angle that equally divides a rotation angle at which a downstream-side end portion in the discharge port is formed and a rotation angle at which an upstream-side end portion in the suction port is formed.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a Continuation of International Patent Application No. PCT/JP2020/023530 filed Jun. 16, 2020, which claims the benefit of priority to Japanese Application No. 2019-141744 filed Jul. 31, 2019, the contents of both of which are incorporated herein by reference in their entireties.

FIELD OF THE INVENTION

The present invention relates to a vane pump device.

BACKGROUND OF THE INVENTION

A vane pump described in Patent Document 1 includes: a rotor which is connected to a rotating shaft pivoted to an inner portion of a housing so as to rotate; a cam ring which is arranged in such a manner as to surround the rotor in the inner portion of the housing; plural vanes which are slidably arranged in plural vane grooves provided in a radial direction of the rotor; plural pump chambers which are defined by the adjacent vanes around the rotor; and plural discharge ports corresponding to the pump chambers carrying out a compression stroke, which are provided to be opposed in a diametrical direction of the rotor. In the vane pump device described in Patent Document 1, the rotor has recess portions formed to be recessed from the outer circumferential surface toward the rotation center direction.

CITATION LIST Patent Literature

Patent Document 1: Japanese Patent Application Laid-Open Publication No. 2013-50067

Technical Problem

In a discharge step, if the step ends even though high-pressure working fluid is not sufficiently discharged, the pressure in the pump chamber remains high despite that the discharge step ends. When a suction step is started, if the pressure in the pump chamber is higher than the pressure in the suction port, the working fluid in the pump chamber flows back to the suction port. If backflow occurs, there is a possibility that the suction port is communicated with the pump chamber to prevent the working fluid from being immediately sucked into the pump chamber from the suction port, to thereby cause delay in starting suction into the pump chamber. Therefore, it is desirable that the pressure in the pump chamber is low when the suction step is started.

An object of the present invention is to provide a vane pump device capable of reducing the pressure in the pump chamber when the suction step is started.

SUMMARY OF THE INVENTION Solution to Problem

The present invention completed under the above object provides a vane pump device including: a rotor rotating while supporting 10 vanes to be movable in a rotation radius direction; and a cam ring having an inner circumferential surface facing an outer circumferential surface of the rotor, wherein a change in a distance from a rotation center of the rotor to the inner circumferential surface of the cam ring in response to a rotation angle of the rotor causes a change in a capacity of a pump chamber, which is partitioned by the outer circumferential surface of the rotor, the inner circumferential surface of the cam ring, and adjacent two of the plural vanes, in response to the rotation angle, the change in the capacity of the pump chamber makes transition to at least a suction step in which working fluid is sucked into the pump chamber and a discharge step in which the working fluid is discharged from the pump chamber, and a starting angle, which is a rotation angle at which the distance starts to increase after a segment having the same distance has reached a predetermined rotation angle, has a rotation angle difference of 2.5 degrees or less with respect to a center angle when the center angle is assumed to be an angle that equally divides the rotation angle at which a downstream-side end portion in a discharge port is formed and the rotation angle at which an upstream-side end portion in a suction port is formed.

Advantageous Effects of Invention

According to the present invention, it is possible to provide a vane pump device capable of reducing the pressure in the pump chamber when the suction step is started.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a part of constituents of a vane pump viewed from a cover side;

FIG. 2 is a perspective view showing a part of constituents of the vane pump viewed from a case side;

FIG. 3 is a cross-sectional view for showing flow paths of high pressure oil in the vane pump;

FIG. 4 is a cross-sectional view for showing flow paths of low pressure oil in the vane pump;

FIG. 5 shows a diagram of a rotor, vanes and a cam ring viewed in one direction of a rotating shaft direction and a diagram thereof viewed in the other direction of the rotating shaft direction;

FIG. 6 is a diagram showing a distance of a cam ring inner circumferential surface of the cam ring from the rotation center per each rotation angle;

FIG. 7 shows a diagram of an inner plate viewed in one direction of the rotating shaft direction and a diagram thereof viewed in the other direction of the rotating shaft direction;

FIG. 8 shows a diagram of an outer plate viewed in the other direction of the rotating shaft direction and a diagram thereof viewed in the one direction of the rotating shaft direction;

FIG. 9 is a diagram of a case viewed in one direction of the rotating shaft direction;

FIG. 10 is a diagram showing the cam ring and the inner plate viewed in one direction;

FIG. 11 is a diagram showing the cam ring and the outer plate viewed in the other direction;

FIG. 12 is a diagram showing a part of the inner circumferential surface of the cam ring with different starting angles;

FIG. 13 shows simulation results of a discharge flow rate in the case where the starting angle is changed;

FIG. 14 is a diagram showing partial change in the volume of the pump chamber at different starting angles;

FIG. 15 is a diagram showing a correlation between the starting angle and the pump capacity; and

FIG. 16 is a diagram showing a part of the inner circumferential surface of the cam ring related to a second modified example.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, an exemplary embodiment according to the present invention will be described in detail with reference to attached drawings.

FIG. 1 is a perspective view showing a part of constituents of a vane pump device 1 related to an exemplary embodiment (hereinafter, referred to as a “vane pump 1”) viewed from a cover 120 side.

FIG. 2 is a perspective view showing a part of constituents of the vane pump 1 viewed from a case 110 side.

FIG. 3 is a cross-sectional view for showing flow paths of high pressure oil in the vane pump 1. FIG. 3 is also a cross-sectional view of the III-III part in FIG. 5.

FIG. 4 is a cross-sectional view for showing flow paths of low pressure oil in the vane pump 1. FIG. 4 is also a cross-sectional view of the IV-IV part in FIG. 5.

The vane pump 1 is a pump driven by, for example, power from an engine of a vehicle, which supplies oil as an example of working fluid to devices such as hydraulic continuously variable transmission and hydraulic power steering.

In addition, the vane pump 1 discharges oil sucked from one inlet 116 from two different outlets, a first outlet 117 and a second outlet 118. The pressure of the oil discharged from the first outlet 117 and the second outlet 118 may be the same or different. More specifically, the vane pump 1 increases pressure of oil, which was sucked from the inlet 116 and then sucked into the pump chamber through the first suction port 2 (refer to FIG. 3), in the pump chamber and discharges thereof from the first discharge port 4 (refer to FIG. 3) and then discharges thereof to the outside from the first outlet 117. In addition, the vane pump 1 increases pressure of oil, which was sucked from the inlet 116 and then sucked into the pump chamber through the second suction port 3 (refer to FIG. 4), in the pump chamber and discharges thereof from the second discharge port 5 (refer to FIG. 4) and then discharges thereof to the outside from the second outlet 118. Note that the first suction port 2, the second suction port 3, the first discharge port 4, and the second discharge port 5 are the portions bordering (facing) the pump chamber.

The vane pump 1 includes: a rotating shaft 10 that receives driving force from the engine or motor of a vehicle to rotate; a rotor 20 that rotates with the rotating shaft 10; plural vanes 30 incorporated into grooves formed in the rotor 20; and a cam ring 40 that surrounds the outer circumference of the rotor 20 and the vanes 30.

The vane pump 1 also includes: an inner plate 50 as an example of a one-side member disposed closer to the one-side end portion side of the rotating shaft 10 than the cam ring 40; and an outer plate 60 as an example of an other-side member disposed closer to the other-side end portion side of the rotating shaft 10 than the cam ring 40.

In addition, the vane pump 1 includes a housing 100 that houses the rotor 20, the plural vanes 30, the cam ring 40, the inner plate 50, and the outer plate 60. The housing 100 has a bottomed cylindrical case 110 and a cover 120 that covers an opening portion of the case 110.

<Configuration of Rotating Shaft 10>

The rotating shaft 10 is rotatably supported by a case-side bearing 111, which will be described later, that is provided in the case 110 and a cover-side bearing 121, which will be described later, that is provided in the cover 120. The rotating shaft 10 includes a spline 11 formed on the outer circumferential surface thereof, and the shaft 10 is coupled to the rotor 20 through the spline 11. In the exemplary embodiment, the rotating shaft 10 rotates by receiving power from a driving source disposed outside of the vane pump 1, such as the engine of the vehicle, and rotationally drives the rotor 20 through the spline 11.

Note that, in the vane pump 1 related to the first exemplary embodiment, the rotating shaft 10 (the rotor 20) is configured to rotate in the clockwise direction in FIG. 1.

<Configuration of Rotor 20>

FIG. 5 shows diagrams of the rotor 20, the vanes 30, and the cam ring 40 viewed in one direction and in the other direction of a rotating shaft direction.

The rotor 20 is a member with an approximate outline of a cylindrical shape. On the inner circumferential surface of the rotor 20, a spline 21, into which the spline 11 (refer to FIG. 1) of the rotating shaft 10 is fitted, is formed. The rotor 20 has arc-shaped curved surface parts 22 around the rotation center C of the rotating shaft 10 in the outer circumferential part. In addition, in the outer circumferential portion of the rotor 20, plural (10 in the exemplary embodiment) vane grooves 23, which concave toward the rotation center C direction from the outer circumferential surface of the rotor 20 to accommodate the vanes 30, are formed at regular intervals (radially) in the circumferential direction. Moreover, in the outer circumferential portion of the rotor 20, rotor concave parts 24, as an example of a first concave part, concaved toward the rotation center C from the curved surface parts 22 are formed.

The curved surface part 22 is formed between two adjacent vane grooves 23.

The vane groove 23 is a groove that opens on the outer circumferential surface of the rotor 20 and on both end surfaces in the rotating shaft direction of the rotating shaft 10 of the rotor 20. When viewed in the rotating shaft direction, as shown in FIG. 5, the vane groove 23 is a rectangle on the outer circumferential portion side with the rotation radius direction being the longitudinal direction and is also circular on the rotation center C side with a diameter larger than the length of the rectangle in the short direction thereof. In other words, the vane groove 23 has a rectangular parallelepiped groove 231 formed in a rectangular parallelepiped shape on the outer circumferential portion side, and a columnar groove 232, as an example of center side space, formed in a columnar shape on the rotation center C side.

The rotor concave part 24 is formed at each of both end portions in the rotating shaft direction. In addition, the rotor concave part 24 is also formed at the center portion in the circumferential direction of the curved surface part 22. The rotor concave part 24 has, as a shape in the rotating shaft direction, a chamfer shape that gradually becomes deeper toward the rotation center C side with the move from the center portion side toward the end portions in the rotating shaft direction.

<Configuration of Vane 30>

The vane 30 is a rectangular parallelepiped member that is incorporated into each of the vane grooves 23 of the rotor 20. The vane 30 has the length in the rotation radius direction that is smaller than the length of the vane groove 23 in the rotation radius direction, and the width that is smaller than the width of the vane groove 23. Then, the vane 30 is held in the vane groove 23 to be movable in the rotation radius direction.

<Configuration of Cam Ring 40>

The cam ring 40 is a member with an approximate outline of a cylindrical shape and includes a cam ring outer circumferential surface 41, a cam ring inner circumferential surface 42, an inner end surface 43, which is an end surface on the inner plate 50 side in the rotating shaft direction, and an outer end surface 44, which is an end surface on the outer plate 60 side in the rotating shaft direction.

The cam ring outer circumferential surface 41 is, when viewed in the rotating shaft direction, as shown in FIG. 5, substantially circular in which the distance from the rotation center C is substantially the same over the whole circumference (except for a certain part).

Note that the vane pump 1 includes 10 vanes 30 that are brought into contact with the cam ring inner circumferential surface 42 of the cam ring 40; thereby, two adjacent vanes 30, the outer circumferential surface of the rotor 20 between the two adjacent vanes 30, the cam ring inner circumferential surface 42 between the two adjacent vanes 30, the inner plate 50, and the outer plate 60 form 10 pump chambers. In the following description, of the two vanes 30 constituting the pump chamber, the vane 30 on the upstream side in the rotating direction is referred to as an upstream-side vane, and the vane 30 on the downstream side in the rotating direction is referred to as a downstream-side vane. As an example, in FIG. 5, of the two vanes 30 constituting the pump chamber on the vertical axis, the upstream-side vane is assigned with the reference sign “31,” and the downstream-side vane is assigned with the reference sign “32.”

FIG. 6 is a diagram showing a distance L of cam ring inner circumferential surface 42 of the cam ring 40 from the rotation center C per each rotation angle.

The inner circumferential surface 42 of the cam ring 40 is, when viewed in the rotating shaft direction, as shown in FIG. 6, formed so that two convex portions are present at a distance L from the rotation center C (refer to FIG. 5) for each rotation angle (to put it another way, the protruding amount of the vane 30 from the vane groove 23). In other words, in the case where the positive vertical axis in the figure viewing in one direction shown in FIG. 5 is assumed to be zero degrees, a first convex portion 42 a is formed by the distance L from the rotation center C gradually increasing from about 20 degrees to about 90 degrees in the counter-clockwise direction and gradually decreasing to about 160 degrees, and a second convex portion 42 b is formed by the distance L from the rotation center C gradually increasing from about 200 degrees to about 270 degrees and gradually decreasing to about 340 degrees. In the cam ring 40 related to the exemplary embodiment, the two convex portions 42 a and 42 b have the same shape.

Note that, in the following description, each of the central rotation angle between the rotation angle at which the downstream-side end portion in the first discharge port 4 is formed and the rotation angle at which the upstream-side end portion in the second suction port 3 is formed, and the central rotation angle between the rotation angle at which the downstream-side end portion in the second discharge port 5 is formed and the rotation angle at which the upstream-side end portion in the first suction port 2 is formed, is sometimes referred to as the “center angle.”

In the cam ring 40, as shown in FIG. 5, an inner concave part 430 including plural concave parts concaved from the inner end surface 43 and an outer concave part 440 including plural concave parts concaved from the outer end surface 44 are formed.

The inner concave part 430 includes, as shown in FIG. 5, a first suction concave part 431 constituting the first suction port 2, a second suction concave part 432 constituting the second suction port 3, a first discharge concave part 433 constituting the first discharge port 4, and a second discharge concave part 434 constituting the second discharge port 5. When viewed in the rotating shaft direction, the first suction concave part 431 and the second suction concave part 432 are formed to be symmetric with respect to the rotation center C, and the first discharge concave part 433 and the second discharge concave part 434 are formed to be symmetric with respect to the rotation center C. In addition, the first suction concave part 431 and the second suction concave part 432 are concaved across the entire region of the inner end surface 43 in the rotation radius direction and concaved at a predetermined angle from the inner end surface 43 in the circumferential direction. The first discharge concave part 433 and the second discharge concave part 434 are concaved from the inner end surface 43 for a predetermined range from the cam ring inner circumferential surface 42 to the cam ring outer circumferential surface 41 in the rotation radius direction and concaved at a predetermined angle from the inner end surface 43 in the circumferential direction.

The outer concave part 440 includes, as shown in the diagram viewed in the other direction shown in FIG. 5, the first suction concave part 441 constituting the first suction port 2, the second suction concave part 442 constituting the second suction port 3, the first discharge concave part 443 constituting the first discharge port 4, and the second discharge concave part 444 constituting the second discharge port 5. When viewed in the rotating shaft direction, the first suction concave part 441 and the second suction concave part 442 are formed to be symmetric with respect to the rotation center C, and the first discharge concave part 443 and the second discharge concave part 444 are formed to be symmetric with respect to the rotation center C. In addition, the first suction concave part 441 and the second suction concave part 442 are concaved across the entire region of the outer end surface 44 in the rotation radius direction and concaved at a predetermined angle from the outer end surface 44 in the circumferential direction. The first discharge concave part 443 and the second discharge concave part 444 are concaved from the outer end surface 44 for a predetermined range from the cam ring inner circumferential surface 42 to the cam ring outer circumferential surface 41 in the rotation radius direction and concaved at a predetermined angle from the outer end surface 44 in the circumferential direction.

In addition, when viewed in the rotating shaft direction, the first suction concave part 431 and the first suction concave part 441 are provided at the same position, and the second suction concave part 432 and the second suction concave part 442 are provided at the same position. The second suction concave part 432 and the second suction concave part 442 are, in the case where the positive vertical axis in the figure viewing in one direction shown in FIG. 5 is assumed to be zero degrees, provided from about 20 degrees to about 90 degrees in the counter-clockwise direction, and the first suction concave part 431 and the first suction concave part 441 are provided from about 200 degrees to about 270 degrees.

In addition, when viewed in the rotating shaft direction, the first discharge concave part 433 and the first discharge concave part 443 are provided at the same position, and the second discharge concave part 434 and the second discharge concave part 444 are provided at the same position. The second discharge concave part 434 and the second discharge concave part 444 are, in the case where the positive vertical axis in the figure viewing in one direction shown in FIG. 5 is assumed to be zero degrees, provided from about 130 degrees to about 175 degrees in the counter-clockwise direction, and the first discharge concave part 433 and the first discharge concave part 443 are provided from about 310 degrees to about 355 degrees.

Moreover, in the cam ring 40, two first discharge through holes 45, which penetrate in the rotating shaft direction to communicate the first discharge concave pat 433 with the first discharge concave part 443, are formed. In addition, in the cam ring 40, two second discharge through holes 46, which penetrate in the rotating shaft direction to communicate the second discharge concave pat 434 with the second discharge concave part 444, are formed.

Moreover, in the cam ring 40, a first through hole 47, which penetrates in the rotating shaft direction to communicate the inner end surface 43 between the first suction concave part 431 and the second discharge concave part 434 with the outer end surface 44 between the first suction concave part 441 and the second discharge concave part 444, is formed. In addition, in the cam ring 40, a second through hole 48, which penetrates in the rotating shaft direction to communicate the inner end surface 43 between the second suction concave part 432 and the first discharge concave part 433 with the outer end surface 44 between the second suction concave part 442 and the first discharge concave part 443, is formed.

<Configuration of Inner Plate 50>

FIG. 7 shows a diagram of the inner plate 50 viewed in one direction of the rotating shaft direction and a diagram thereof viewed in the other direction of the rotating shaft direction.

The inner plate 50 is a member with an approximate outline of a circular plate shape with a through hole formed at the center portion thereof and includes an inner plate outer circumferential surface 51, an inner plate inner circumferential surface 52, an inner plate cam-ring side end surface 53, which is an end surface on the cam ring 40 side in the rotating shaft direction, and an inner plate non cam-ring side end surface 54, which is an end surface on the side opposite to the cam ring 40 side in the rotating shaft direction.

The inner plate outer circumferential surface 51 is, when viewed in the rotating shaft direction, circular as shown in FIG. 7, and the distance from the rotation center C is substantially the same as the distance of the cam ring outer circumferential surface 41 of the cam ring 40 from the rotation center C.

The inner plate inner circumferential surface 52 is, when viewed in the rotating shaft direction, circular as shown in FIG. 7, and the distance from the rotation center C is substantially the same as the distance to the bottom of the groove in the spline 21 (refer to FIG. 5) formed on the inner circumferential surface of the rotor 20.

In the inner plate 50, an inner plate cam-ring side concave part 530 configured with plural concave parts concaved from the inner plate cam-ring side end surface 53 and an inner plate non cam-ring side concave part 540 configured with plural concave parts concaved from the inner plate non cam-ring side end surface 54 are formed.

The inner plate cam-ring side concave part 530 includes a first suction concave part 531 formed at a position facing the first suction concave part 431 of the cam ring 40 to constitute the first suction port 2 and a second suction concave part 532 formed at a position facing the second suction concave part 432 of the cam ring 40 to constitute the second suction port 3. The first suction concave part 531 and the second suction concave part 532 are formed to be symmetric with respect to the rotation center C.

The first suction concave part 531 includes a first suction inside part 538 constituting a portion on the rotation center C side of the first suction port 2. The second suction concave part 532 includes a second suction inside part 539 constituting a portion on the rotation center C side of the second suction port 3. These first suction inside part 538 and the second suction inside part 539 will be described in detail later.

Moreover, the inner plate cam-ring side concave part 530 includes a second discharge concave part 533 formed at a position facing the second discharge concave part 434 of the cam ring 40.

The inner plate cam-ring side concave part 530 also includes an inner plate second concave part 534 at a position corresponding to the second suction concave part 532 through the second discharge concave part 533 in the circumferential direction and at a position facing the columnar groove 232 of the vane groove 23 in the rotor 20 in the rotation radius direction.

In addition, the inner plate cam-ring side concave part 530 includes an inner plate first concave part 535 at a position corresponding to the first discharge concave part 433 in the circumferential direction and at a position facing the columnar groove 232 of the vane groove 23 in the rotor 20 in the rotation radius direction.

The inner plate cam-ring side concave part 530 also includes a first concave part 536 formed at a position facing the first through hole 47 of the cam ring 40 and a second concave part 537 formed at a position facing the second through hole 48.

The inner plate non cam-ring side concave part 540 includes an outer circumferential side groove 541, which is a groove formed at the outer circumferential portion and into which an outer circumferential side O-ring 57 (refer to FIG. 3) is fitted, and an inner circumferential side groove 542, which is a groove formed at the inner circumferential portion and into which an inner circumferential side O-ring 58 (refer to FIG. 3) is fitted. The outer circumferential side O-ring 57 and the inner circumferential side O-ring 58 seal the gap between the inner plate 50 and case 110.

Moreover, in the inner plate 50, a first discharge through hole 55, which penetrates in the rotating shaft direction, is formed at a position facing the first discharge concave part 443 of the cam ring 40. The opening portion in the first discharge through hole 55 on the cam ring 40 side and the opening portion of the second discharge concave part 533 are formed to be symmetric with respect to the rotation center C.

In addition, in the inner plate 50, an inner plate first through hole 56, which is a hole penetrating in the rotating shaft direction, is formed at a position corresponding to the first discharge concave part 531 in the circumferential direction and at a position facing the columnar groove 232 of the vane groove 23 in the rotor 20 in the rotation radius direction.

<Configuration of Outer Plate 60>

FIG. 8 shows a diagram of the outer plate 60 viewed in the other direction of the rotating shaft direction and a diagram thereof viewed in the one direction of the rotating shaft direction.

The outer plate 60 is a member with an approximate outline of a plate shape with a through hole formed at the center portion thereof and includes an outer plate outer circumferential surface 61, an outer plate inner circumferential surface 62, an outer plate cam-ring side end surface 63, which is an end surface on the cam ring 40 side in the rotating shaft direction, and an outer plate non cam-ring side end surface 64, which is an end surface on the side opposite to the cam ring 40 side in the rotating shaft direction.

When viewed in the rotating shaft direction, as shown in FIG. 8, the outer plate outer circumferential surface 61 is in a circular shape as a base including cutouts at two locations. The distance of the circular shape as the base from the rotation center C is substantially the same as the distance in the cam ring outer circumferential surface 41 of the cam ring 40 from the rotation center C. The cutouts at the two locations include a first suction cutout part 611 formed at a position facing the first suction concave part 441 to constitute the first suction port 2 and a second suction cutout part 612 formed at a position facing the second suction concave part 442 to constitute the second suction port 3. The outer plate outer circumferential surface 61 is formed to be symmetric with respect to the rotation center C, and the first suction cutout part 611 and the second suction cutout part 612 are formed to be symmetric with respect to the rotation center C.

The outer plate inner circumferential surface 62 is, when viewed in the rotating shaft direction, circular as shown in FIG. 8, and the distance from the rotation center C is substantially the same as the distance to the bottom of the groove in the spline 21 formed on the inner circumferential surface of the rotor 20.

In the outer plate 60, an outer plate cam-ring side concave part 630 configured with plural concave parts concaved from the outer plate cam-ring side end surface 63 is formed.

The outer plate cam-ring side concave part 630 includes a first discharge concave part 631 formed at a position facing the first discharge concave part 443 of the cam ring 40.

The outer plate cam-ring side concave part 630 also includes an outer plate first concave part 632 at a position corresponding to the first suction cutout part 611 through the first discharge concave part 631 in the circumferential direction and at a position facing the columnar groove 232 of the vane groove 23 in the rotor 20 in the rotation radius direction.

In addition, the outer plate cam-ring side concave part 630 includes an outer plate second concave part 633 at a position corresponding to the second discharge concave part 444 of the cam ring 40 in the circumferential direction and at a position facing the columnar groove 232 of the vane groove 23 in the rotor 20 in the rotation radius direction.

Moreover, the outer plate cam-ring side concave part 630 includes a first V-groove 634 that is in parallel with the rotating shaft direction, has a V-shaped cross section cut with a plane perpendicular to the outer plate outer circumferential surface 61, and has the concave depth increasing with the move from the upstream side to the downstream side in the rotating direction. The downstream-side end portion of the first V-groove 634 is connected to the upstream-side end portion of the first discharge concave part 631.

The outer plate cam-ring side concave part 630 also includes a second V-groove 635 that is in parallel with the rotating shaft direction, has a V-shaped cross section cut with a plane perpendicular to the outer plate outer circumferential surface 61, and has the concave depth increasing with the move from the upstream side to the downstream side in the rotating direction. The downstream-side end portion of the second V-groove 635 is connected to the upstream-side end portion of the second discharge concave part 65.

Moreover, in the outer plate 60, a second discharge through hole 65, which penetrates in the rotating shaft direction, is formed at a position facing the second discharge concave part 444 of the cam ring 40. The opening portion in the second discharge through hole 65 on the cam ring 40 side and the opening portion of the first discharge concave part 631 are formed to be symmetric with respect to the rotation center C.

In addition, in the outer plate 60, an outer plate second through hole 66, which is a hole penetrating in the rotating shaft direction, is formed at a position corresponding to the second suction cutout part 612 in the circumferential direction and at a position facing the columnar groove 232 of the vane groove 23 in the rotor 20 in the rotation radius direction.

Moreover, in the outer plate 60, a first through hole 67, which is a hole penetrating in the rotating shaft direction, is formed at a position facing the first through hole 47 of the cam ring 40, and a second through hole 68, which is a hole penetrating in the rotating shaft direction, is formed at a position facing the second through hole 48 of the cam ring 40.

<Configuration of Housing 100>

The housing 100 includes the rotor 20, the vanes 30, the cam ring 40, the inner plate 50, and the outer plate 60. In addition, the housing 100 houses one end portion of the rotating shaft 10 inside thereof and protrudes the other end portion.

The case 110 and the cover 120 are fastened by bolts.

(Configuration of Case 110)

FIG. 9 is a diagram of the case 110 viewed in one direction of the rotating shaft direction.

The case 110 is a bottomed cylindrical member and includes the case-side bearing 111 rotatably supporting one end portion of the rotating shaft 10 at the center portion of the bottom portion.

The case 110 also has an inner plate fitting part 112 into which the inner plate 50 is fitted. The inner plate fitting part 112 includes an inner-diameter side fitting part 113 existing at a position close to the rotation center C (inner diameter side), and an outer-diameter side fitting part 114 existing at a position away from the rotation center C (outer diameter side).

The inner-diameter side fitting part 113 is, as shown in FIG. 3, provided on the outer diameter side of the case-side bearing 111, and includes an inner-diameter side cover part 113 a covering surroundings of part of the inner plate inner circumferential surface 52 of the inner plate 50 and an inner-diameter side suppression part 113 b suppressing movement of the inner plate 50 toward the bottom portion. The inner-diameter side cover part 113 a is, when viewed in the rotating shaft direction, in a circular shape in which the distance thereof from the rotation center C is smaller than the distance of the inner plate inner circumferential surface 52 from the rotation center C. The inner-diameter side suppression part 113 b is a doughnut-shaped surface perpendicular to the rotating shaft direction, in which the distance in the inner circle from the rotation center C is the same as the distance in the inner-diameter side cover part 113 a from the rotation center C, and the distance in the outer circle from the rotation center C is smaller than the distance in the inner plate inner circumferential surface 52 from the rotation center C.

The outer-diameter side fitting part 114 includes, as shown in FIG. 3, an outer-diameter side cover part 114 a covering surroundings of part of the inner plate outer circumferential surface 51 of the inner plate 50 and an outer-diameter side suppression part 114 b suppressing movement of the inner plate 50 toward the bottom portion. The outer-diameter side cover part 114 a is, when viewed in the rotating shaft direction, in a circular shape in which the distance thereof from the rotation center C is larger than the distance of the inner plate outer circumferential surface 51 from the rotation center C. The outer-diameter side suppression part 114 b is a doughnut-shaped surface perpendicular to the rotating shaft direction, in which the distance in the outer circle from the rotation center C is the same as the distance in the outer-diameter side cover part 114 a from the rotation center C, and the distance in the inner circle from the rotation center C is smaller than the distance in the inner plate outer circumferential surface 51 from the rotation center C.

The inner plate 50 is inserted toward the bottom portion side until the inner circumferential side O-ring 58, which is fitted into the inner circumferential side groove 542 of the inner plate 50, butts the inner-diameter side suppression part 113 b, and the outer circumferential side O-ring 57, which is fitted into the outer circumferential side groove 541, butts the outer-diameter side suppression part 114 b. Then, the inner circumferential side O-ring 58 is brought into contact with the inner circumferential side groove 54 of the inner plate 50, the inner-diameter side cover part 113 a and the inner-diameter side suppression part 113 b of the case 110, and the outer circumferential side O-ring 57 is brought into contact with the outer circumferential side groove 541 of the inner plate 50, the outer-diameter side cover part 114 a and the outer-diameter side suppression part 114 b of the case 110, to thereby seal the case 110 and the inner plate 50. Consequently, in the case 110, space S1 closer to the opening portion than the inner plate fitting part 112 and space S2 closer to the bottom portion than the inner plate fitting part 112 are partitioned. The space S1 closer to the opening portion than the inner plate fitting part 112 constitutes a suction flow path R1 where oil sucked from the first suction port 2 and the second suction port 3 is circulated. The space S2 closer to the bottom portion than the inner plate fitting part 112 constitutes a first discharge flow path R2 where oil discharged from the first discharge port 4 is circulated.

Moreover, in the case 110, separate from the container space that contains the rotor 20, the vanes 30, the cam ring 40, the inner plate 50 and the outer plate 60, on the outside of the container space in the rotation radius direction, a case outer concave part 115 concaved from the opening portion side toward the rotating shaft direction is formed. The case outer concave part 115 faces a cover outer concave part 123, which will be described later, formed in the cover 120, and constitutes a case second discharge flow path R3 where the oil discharged from the second discharge port 5 is circulated.

In addition, in the case 110, as shown in FIG. 1, the inlet 116, which communicates the space S1 closer to the opening portion than the inner plate fitting part 112 and the outside of the case 110, is formed. The inlet 116 is configured to include a columnar-shaped hole formed on the side wall of the case 110, which is also a hole with the direction perpendicular to the rotating shaft direction being the columnar direction. The inlet 116 constitutes the suction flow path R1 where oil sucked from the first suction port 2 and the second suction port 3 is circulated.

In addition, in the case 110, as shown in FIG. 1, the first outlet 117 communicating the space S1 closer to the bottom portion than the inner plate fitting part 112 with the outside of the case 110 is formed. The first outlet 117 is configured to include a columnar-shaped hole formed on the side wall of the case 110, which is also a hole with the direction perpendicular to the rotating shaft direction being the columnar direction. The first outlet 117 constitutes the first discharge flow path R2 where oil discharged from the first discharge port 4 is circulated.

In addition, in the case 110, as shown in FIG. 1, the second outlet 118 communicating the case outer concave part 115 with the outside of the case 110 is formed. The second outlet 118 is configured to include a columnar-shaped hole formed on the side wall of the case outer concave part 115 in the case 110, which is also a hole with the direction perpendicular to the rotating shaft direction being the columnar direction. The second outlet 118 constitutes the case second discharge flow path R3 where oil discharged from the second discharge port 5 is circulated.

(Configuration of Cover 120)

As shown in FIG. 2, the cover 120 includes the cover-side bearing 121 rotatably supporting the rotating shaft 10 at the center portion.

In the cover 120, a second discharge concave part 122 concaved from the end surface on the case 110 side toward the rotating shaft direction is formed at a position facing the second through hole 65 and the outer plate second through hole 66 of the outer plate 60.

In addition, in the cover 120, the cover outer concave part 123 concaved from the end surface on the case 110 side toward the rotating shaft direction in the outside than the cover second discharge concave part 122 in the rotation radius direction and a cover concave part connection part 124 connecting the cover second discharge concave part 122 and the cover outer concave part 123 in the other direction of the rotating shaft direction than the end surface on the case 110 side are formed. The cover outer concave part 123 is formed to open at a position not facing the above-described container space formed in the case 110, and faces the cover outer concave part 115. The cover second discharge concave part 122, the cover concave part connection part 124, and the cover outer concave part 123 constitute a cover second discharge flow path R4 (refer to FIG. 4) where oil discharged from the second discharge port 5 is circulated. The oil discharged from the second discharge port 5 flows into the case second discharge flow path R3 via the cover concave part connection part 124 and also flows into the outer plate second through hole 66 via the cover second discharge concave part 122.

Moreover, in the cover 120, a cover suction concave part 125, which is concaved from the end surface on the case 110 side toward the rotating shaft direction, is formed at portions facing the first suction cutout part 611 and the second suction cutout part 612 of the outer plate 60 and at a portion that is the space S1 closer to the opening portion than the inner plate fitting part 112 of the case 110 and faces the space outside of the cam ring outer circumferential surface 41 of the cam 40 in the rotation radius direction.

The cover suction concave part 125 constitutes the suction flow path R1 where oil sucked from the inlet 116, and then sucked into the pump chamber through the first suction port 2 and the second suction port 3 is circulated.

In addition, in the cover 120, a first cover concave part 127 and a second cover concave part 128 that are concaved from the end surface on the case 110 side toward the rotating shaft direction are formed at positions facing the first through hole 67 and the second through hole 68, respectively, of the outer plate 60.

<Action of Vane Pump 1>

The vane pump 1 related to the exemplary embodiment includes the 10 vanes 30 that are brought into contact with the cam ring inner circumferential surface 42 of the cam ring 40, and thereby includes 10 pump chambers each formed by two adjacent vanes 30, the outer circumferential surface of the rotor 20 between the two adjacent vanes 30, the cam ring inner circumferential surface 42 between the two adjacent vanes 30, the inner plate cam-ring side end surface 53 of the inner plate 50, and the outer plate cam-ring side end surface 63 of the outer plate 60. Focusing on one pump chamber, the rotating shaft 10 is rotated one time and the rotor 20 is rotated one time, and thereby the pump chamber is rotated one time around the rotating shaft 10. In the process of one rotation of the pump chamber, the oil sucked from the first suction port 2 is compressed to increase the pressure thereof and discharged from the first discharge port 4, as well as the oil sucked from the second suction port 3 is compressed to increase the pressure thereof and discharged from the second discharge port 5.

<Starting Angle>

In the following, a rotation angle at which the distance L of the cam ring inner circumferential surface 42 of the cam ring 40 from the rotation center C starts to increase (hereinafter, referred to as a “starting angle”) will be described. The starting angle is the rotation angle at which the distance L starts to increase after a segment with the minimum distance L has reached a predetermined rotation angle. The predetermined rotation angle is, for example, 9 degrees. In the case where the predetermined rotation angle is 9 degrees, the ratio of the predetermined rotation angle to the rotation angle between the two vanes 30 constituting the pump chamber (the rotation angle between the vanes) is 9/(360/10)=0.25. It can be shown as an example that the ratio of the predetermined rotation angle to the rotation angle between the vanes is 0.11 or more. The segment of the predetermined rotation angle with the minimum distance L and the starting angle are provided between the discharge port and the suction port.

Here, the first suction port 2 is configured with the first suction concave parts 431 and 441 formed in the cam ring 40, the first suction concave part 531 formed in the inner plate 50, and the first suction cutout part 611 formed in the outer plate 60.

The second suction port 3 is configured with the second suction concave parts 432 and 442 formed in the cam ring 40, the second suction concave part 532 formed in the inner plate 50, and the second suction cutout part 612 formed in the outer plate 60.

The first discharge port 4 is configured with the first discharge concave parts 433 and 443 formed in the cam ring 40, the first discharge through hole 55 formed in the inner plate 50, and the first discharge concave part 631 formed in the outer plate 60.

The second discharge port 5 is configured with the second discharge concave parts 434 and 444 formed in the cam ring 40, the second discharge concave part 533 formed in the inner plate 50, and the second discharge through hole 65 formed in the outer plate 60.

In the following description, in the case where it is not necessary to distinguish the first suction port 2 and the second suction port 3, the first suction port 2 and the second suction port 3 are collectively referred to as the “suction port” in some cases. In addition, in the case where it is not necessary to distinguish the first discharge port 4 and the second discharge port 5, the first discharge port 4 and the second discharge port 5 are collectively referred to as the “discharge port” in some cases.

The vane pump 1 related to the above-described exemplary embodiment includes the rotor 20 that rotates while supporting the 10 vanes 30 to be movable in the rotation radius direction and the cam ring 40 having the inner circumferential surface that faces the outer circumferential surface of the rotor 20, and the volume of the pump chamber changes with the rotation of the rotor 20. The change in the volume of the pump chamber causes transition to at least the suction step and the discharge step.

The suction step is the step to suck the oil via the suction port. The segment of the suction step is the segment to suck the oil via the suction port. The discharge step is the step to discharge the oil via the discharge port. The segment of the discharge step is the segment to discharge the oil via the discharge port.

Hereinafter, the rotation angle at which the discharge step is finished and the rotation angle at which the suction step is started will be described.

In the following description, of the two vanes 30 constituting the pump chamber, the vane 30 on the upstream side is referred to as the upstream-side vane, and the vane 30 on the downstream side is referred to as the downstream-side vane.

The rotation angle at which the discharge step is finished is the rotation angle at which the upstream-side vane passes through the downstream-side end portion (hereinafter, sometimes referred to as the “downstream end”) of the discharge port. The upstream-side vane passes through the downstream end of the discharge port, and thereby the oil is prevented from being discharged into the pump chamber via the discharge port.

The rotation angle at which the suction step is started is the rotation angle at which the downstream-side vane passes through the upstream-side end portion (hereinafter, sometimes referred to as the “upstream end”) of the suction port. The downstream-side vane passes through the upstream end of the suction port, and thereby sucking of the oil from the pump chamber via the suction port is started.

FIG. 10 is a diagram showing the cam ring 40 and the inner plate 50 viewed in one direction.

FIG. 11 is a diagram showing the cam ring 40 and the outer plate 60 viewed in the other direction.

Hereinafter, the rotation angle at which the discharge step is finished and the rotation angle at which the suction step is started will be described. Note that, since the first side and the second side are symmetric with respect to a point, detailed description will be given of the first side in the following, and the detailed description of the second side will be omitted.

Since all the rotation angles of the downstream ends of the first discharge concave parts 433 and 443 formed in the cam ring 40, the first discharge through hole 55 formed in the inner plate 50, and the first discharge concave part 631 formed in the outer plate 60 constituting the first discharge port 4 are the same, the rotation angle to be the downstream-side end portion (the downstream end) of the first discharge port 4 is the rotation angle of the downstream ends of these components. For example, the downstream end of the cam ring 40 is the first discharge concave part downstream end 433 f (443 f), which is the downstream end in the first discharge concave part 433 (443) formed in cam ring 40, as shown in FIGS. 10 and 11. Moreover, the downstream end of the inner plate 50 is, for example, the first discharge through hole downstream end 55 f, which is the downstream end in the first discharge through hole 55 formed in the inner plate 50, as shown in FIG. 10. In addition, the downstream end of the outer plate 60 is the first discharge concave part downstream end 631 f, which is the downstream end in the first discharge concave part 631 formed in the outer plate 60, as shown in FIG. 11.

Since all the rotation angles of the downstream ends of the second discharge concave parts 434 and 444 formed in the cam ring 40, the second discharge concave part 533 formed in the inner plate 50, and the second discharge through hole 65 formed in the outer plate 60 constituting the second discharge port 5 are the same, the rotation angle to be the downstream-side end portion (the downstream end) of the second discharge port 5 is the rotation angle of the downstream ends of these components. For example, the downstream end of the cam ring 40 is the second discharge concave part downstream end 434 f (444 f), which is the downstream end in the second discharge concave part 434 (444) formed in cam ring 40, as shown in FIGS. 10 and 11. Moreover, the downstream end of the inner plate 50 is, for example, the second discharge concave part downstream end 533 f, which is the downstream end in the second discharge concave part 533 formed in the inner plate 50, as shown in FIG. 10. In addition, the downstream end of the outer plate 60 is the second discharge through hole downstream end 65 f, which is the downstream end in the second discharge through hole 65 formed in the outer plate 60, as shown in FIG. 11.

Since all the rotation angles of the upstream ends of the first suction concave parts 431 and 441 formed in the cam ring 40, the first suction concave part 531 formed in the inner plate 50, and the first suction cutout part 611 formed in the outer plate 60 constituting the first suction port 2 are the same, the rotation angle to be the upstream end of the first suction port 2 is the rotation angle of the upstream ends of these components. For example, the upstream end of the cam ring 40 is the first suction concave part upstream end 431 e (441 e), which is the upstream end in the first suction concave part 431 (441) formed in cam ring 40, as shown in FIGS. 10 and 11. Moreover, the upstream end of the inner plate 50 is, for example, the first suction concave part upstream end 531 e, which is the upstream end in the first suction concave part 531 formed in the inner plate 50, as shown in FIG. 10. In addition, the upstream end of the outer plate 60 is the first suction cutout part upstream end 611 e, which is the upstream end in the first suction cutout part 611 formed in the outer plate 60, as shown in FIG. 11.

Since all the rotation angles of the upstream ends of the second suction concave parts 432 and 442 formed in the cam ring 40, the second suction concave part 532 formed in the inner plate 50, and the second suction cutout part 612 formed in the outer plate 60 constituting the second suction port 3 are the same, the rotation angle to be the upstream end of the second suction port 3 is the rotation angle of the upstream ends of these components. For example, the upstream end of the cam ring 40 is the second suction concave part upstream end 432 e (442 e), which is the upstream end in the second suction concave part 432 (442) formed in cam ring 40, as shown in FIGS. 10 and 11. Moreover, the upstream end of the inner plate 50 is, for example, the second suction concave part upstream end 532 e, which is the upstream end in the second suction concave part 532 formed in the inner plate 50, as shown in FIG. 10. In addition, the upstream end of the outer plate 60 is the second suction cutout part upstream end 612 e, which is the upstream end in the second suction cutout part 612 formed in the outer plate 60, as shown in FIG. 11.

Here, usually, the rotation angle between the suction port and the discharge port is substantially the same as the rotation angle of the two adjacent vanes; for example, in a vane pump device of 10-vane specifications, the rotation angle of the two adjacent vanes 30 is 36 degrees (360 degrees/10=36 degrees), and the angle between the suction port and the discharge port is also substantially 36 degrees.

Further, the above-described vane pump device of the 10-vane specifications will be described in detail.

Usually, there are included a rotor that rotates while supporting plural vanes to be movable in the rotation radius direction, and a cam ring having an inner circumferential surface facing an outer circumferential surface of the rotor, and the distance from the rotation center of the rotor to the inner circumferential surface of the cam ring changes in response to the rotation angle of the rotor, to thereby change the volume of the pump chamber, which is partitioned by the outer circumferential surface of the rotor, the inner circumferential surface of the cam ring, and two adjacent vanes among the plural vanes, in response to the rotation angle.

Then, the volume of the pump chamber becomes minimum when the two adjacent vanes are present between the suction port and the discharge port, where the distance to the inner circumferential surface of the cam ring is minimum (for example, FIG. 5 shows a state of the two adjacent vanes present between the suction port and the discharge port, where the upstream-side vane 31 is positioned at the downstream-side end portion in the discharge port and the downstream-side vane 32 is positioned at the upstream-side end portion in the suction port).

Further, the starting angle, which is the rotation angle at which the distance starts to increase after the segment having the minimum distance has reached the predetermined rotation angle, is matched with a suction port starting point (the rotation angle at which the suction step is started), and the rotation angle at which the distance becomes minimum, which has been maximum, is matched with a discharge port finishing point (the rotation angle at which the discharge step is finished).

In the above-described vane pump device, the volume of the pump chamber when suction is started becomes minimum, and the volume of the pump chamber increases with the rotation from the point. Then, when the upstream-side vane of the two vanes matches with the downstream side of the suction port, the distance of the pump chamber to the inner circumferential surface of the cam ring becomes maximum, and the volume also becomes maximum. Thereafter, the distance to the inner circumferential surface of the cam ring is reduced, and the step of minimizing the volume when the two adjacent vanes are present between the suction port and the discharge port where the distance to the inner circumferential surface of the cam ring is minimum is repeated.

In the vane pump device, due to the reduction in the discharge flow rate, the apparent pump performance is degraded. Previously, to avoid pump performance degradation, the starting angle was not shifted toward the upstream side in the rotation direction. However, as a result of consideration by the inventor, it was found to be possible to provide a vane pump device capable of reducing the pressure in the pump chamber when the suction step is started by shifting the starting angle toward the upstream side in the rotation direction than before. The present invention was completed based on such finding.

In the vane pump 1 related to the exemplary embodiment, the starting angle is set within a range of the rotation angle difference of 2.5 degrees on the upstream side in the rotation direction from the center angle and the rotation angle difference of 2.5 degrees on the downstream side in the rotation direction from the center angle, the center angle being the rotation angle at the center between the rotation angle at which the downstream-side end portion (downstream end) in the discharge port is formed and the rotation angle at which the upstream-side end portion (upstream end) in the suction port is formed (refer to FIG. 13). In other words, the starting angle is set at the rotation angle difference of 2.5 degrees or less with respect to the center angle when the center angle is the angle equally divides the rotation angle at which the downstream-side end portion in the discharge port is formed and the rotation angle at which the upstream-side end portion in the suction port is formed. This is due to the following reasons.

FIG. 12 is a diagram showing a part of the cam ring inner circumferential surface 42 with different starting angles. FIG. 12 enlarges the XII part in FIG. 6.

FIG. 13 shows simulation results indicating discharge flow rates with different starting angles.

A configuration with the starting angle with 12.5 degrees of rotation angle difference from the center angle on the downstream side in the rotation direction is assumed to be a comparative configuration, and the discharge flow rates of the four types of configurations A to D with different starting angles were compared with the discharge flow rate of the comparative configuration. The configuration A has the starting angle with 2.5 degrees of rotation angle difference from the center angle on the upstream side in the rotation direction. The configuration B has the starting angle with 1.25 degrees of rotation angle difference from the center angle on the upstream side in the rotation direction. The configuration C has the starting angle with zero degrees (0 degrees) of rotation angle difference from the center angle, that is, the starting angle is the same as the center angle. The configuration D has the starting angle with 2.5 degrees of rotation angle difference from the center angle on the downstream side in the rotation direction. Assuming that the rotation angle of the center angle is 0 degrees, the downstream-side direction in the rotation direction is positive, and the upstream-side direction in the rotation direction is negative, the starting angles of the configurations A, B, C, D, and the comparative configuration are −2.5 degrees, −1.25 degrees, 0 degrees, 2.5 degrees, and 12.5 degrees, respectively. Note that, in the configurations A to D and the comparative configuration, the highest points of the above-described convex portions drawn by the distances L of the respective rotation angles and the rotation angles providing the highest points are the same, and the starting angles are different. Therefore, in the process to reach the rotation angle providing the highest point from the starting angle, the configurations A, B, C, D, and the comparative configuration are in the ascending order of the amount of change in the distance L per unit rotation angle (the inclination angle of the distance L in FIG. 6).

The discharge flow rate is the volume of oil that is discharged in one minute from the first outlet 117 and the second outlet 118, and the unit thereof is L/min.

As shown in FIG. 13, the discharge flow rate of the configuration A is 1.17 times the discharge flow rate of the comparative configuration, the discharge flow rate of the configuration B is 1.18 times the discharge flow rate of the comparative configuration, the discharge flow rate of the configuration C is 1.19 times the discharge flow rate of the comparative configuration, and the discharge flow rate of the configuration D is 1.15 times the discharge flow rate of the comparative configuration.

As shown in FIG. 13, by shifting the starting angle on the upstream side of the starting angle of the comparative configuration in the rotation direction, the discharge flow rate becomes higher than the discharge flow rate of the comparative configuration. This is due to the following reasons.

In the discharge step, if the step is finished even though the high-pressure oil is not sufficiently discharged, the pressure in the pump chamber remains high despite that the discharge step is finished. Then, when the suction step is started, if the pressure in the pump chamber is higher than the pressure in the suction port, the oil in the pump chamber flows back to the suction port. The backflow is likely to occur even though the first V-groove 634 or the second V-groove 635 is formed. If the backflow occurs, there is a possibility that the suction port is communicated with the pump chamber to prevent the oil from being immediately sucked into the pump chamber from the suction port, to thereby cause delay in starting suction into the pump chamber. If the delay is caused in starting suction of oil into the pump chamber, the volume of oil to be sucked into the pump chamber in the suction step is reduced. As the volume of oil to be sucked is reduced, the discharge flow rate is also reduced. As a result, the pump efficiency is decreased. In addition, if the backflow occurs, noise associated with the backflow or noise of collapse of bubbles (air) contained in the oil caused by the backflow is likely to be generated.

FIG. 14 is a diagram showing partial change in the volume V of the pump chamber at different starting angles.

Here, it is assumed that the rotation angle of the upstream-side vane, of the two vanes 30 constituting the pump chamber, is the rotation angle of the pump chamber, and the volume V of the pump chamber configured by including the upstream-side vane is the volume V at the rotation angle. In other words, when the rotation angle of the upstream-side vane is zero degrees (when the center of the upstream-side vane in the rotation direction is on the positive vertical axis in the figure viewed in one direction shown in FIG. 5), the volume V of the pump chamber configured by including the upstream-side vane is assumed to be the volume V at the rotation angle of zero degrees. Since the vane 30 has a thickness in the rotation direction, the rotation angle of the vane 30 is based on the center in the rotation direction.

As shown in FIG. 14, in the comparative configuration, when the rotation angle difference from the center angle is substantially 19 degrees toward the upstream side in the rotation direction, the volume V is the minimum. In the configuration A, when the rotation angle difference from the center angle is substantially 30 degrees toward the upstream side in the rotation direction, the volume V is the minimum. In the configuration B, when the rotation angle difference from the center angle is substantially 29 degrees toward the upstream side in the rotation direction, the volume V is the minimum. In the configuration C, when the rotation angle difference from the center angle is substantially 27.5 degrees toward the upstream side in the rotation direction, the volume V is the minimum. In the configuration D, when the rotation angle difference from the center angle is substantially 25 degrees toward the upstream side in the rotation direction, the volume V is the minimum.

In other words, in the configurations A to D and the comparative configuration, the distance L is, on the upstream side of the segment having the minimum distance L in the rotation direction, gradually reduced with the move from the upstream side toward the downstream side in the rotation direction, and on the downstream side of the starting angle in the rotation direction, gradually increased with the move from the upstream side toward the downstream side in the rotation direction. Then, in the case where the downstream-side vane is present in the segment where the distance L is the minimum and the upstream-side vane is present in the segment where the distance L is gradually reduced, the volume V of the pump chamber is reduced with the move from the upstream side toward the downstream side in the rotation direction, and thereafter, due to the shift of the downstream-side vane to the segment where the distance L is gradually increased, the volume V of the pump chamber is increased even though the upstream-side vane is present in the segment where the distance is gradually reduced.

Between the rotation angle at the downstream end of the discharge port and the rotation angle at the upstream end of the suction port, in the case where the rotation angles are the same, the starting angle of the vane pump 1 related to the exemplary embodiment positioned on the upstream side in the rotation direction as compared to the starting angle of the comparative configuration makes the distance L in the exemplary embodiment larger than the distance L in the comparative configuration. Therefore, between the rotation angle at the downstream end of the discharge port and the rotation angle at the upstream end of the suction port, in the case where the rotation angles are the same, the volume V of the pump chamber in the exemplary embodiment is larger than the volume V of the pump chamber in the comparative configuration. Thus, regarding the pressure in the pump chamber having reached the rotation angle at which the suction step is started, the pressure in the vane pump 1 in the exemplary embodiment is lower than the pressure in the vane pump in the comparative configuration. As a result, upon reaching the rotation angle at which the suction step is started, the backflow of oil from the pump chamber into the suction port is less likely to occur, and thereby the delay in starting suction of oil into the pump chamber hardly occurs. Therefore, the volume of oil to be sucked into the pump chamber during the suction step is less likely to be reduced. In other words, the volume of oil sucked into the pump chamber during the suction step of the vane pump 1 related to the exemplary embodiment becomes larger than the volume of oil sucked into the pump chamber during the suction step of the vane pump related to the comparative configuration. Then, as the volume of oil to be sucked is increased, the discharge flow rate is also increased. As a result, the pump efficiency is increased.

Then, as shown in FIG. 13, the discharge flow rate is the highest in the configuration C in which the rotation angle difference between the starting angle and the center angle is zero degrees, that is, the starting angle and the center angle are the same, and the discharge flow rate is gradually reduced as the starting angle is away from the center angle. Therefore, it is most preferable that the starting angle and the center angle are the same.

However, as shown in FIG. 13, for example, even though the starting angle was 2.5 degrees away from the center angle, the discharge flow rate of the configuration A, in which the starting angle was on the upstream side of the center angle in the rotation direction, was 1.17 times the discharge flow rate of the comparative configuration, and the discharge flow rate of the configuration D, in which the starting angle was on the downstream side of the center angle in the rotation direction, was 1.15 times the discharge flow rate of the comparative configuration. Therefore, in the case where the starting angle is within the range from the position of the rotation angle difference of 2.5 degrees on the upstream side from the center angle in the rotation direction to the position of the rotation angle difference of 2.5 degrees on the downstream side from the center angle in the rotation direction, the discharge flow rate is 1.15 times or more the discharge flow rate of the comparative configuration. Therefore, the starting angle may be 2.5 degrees away from the center angle.

On the other hand, if the starting angle is too far from the center angle on the upstream side in the rotation direction, in other words, if the starting angle is too close to the rotation angle at the downstream end of the discharge port, the pump capacity is reduced. The pump capacity is the volume of oil that can be sucked and discharged during one rotation in a single pump chamber, and the unit thereof is cc/rev.

FIG. 15 is a diagram showing a correlation between the starting angle and the pump capacity.

As shown in FIG. 15, the pump capacity of the configuration A was 1.00 times the pump capacity of the comparative configuration, and the pump capacity of the configuration B was 1.005 times the pump capacity of the comparative configuration. In addition, the pump capacity of the configuration C was 1.006 times the pump capacity of the comparative configuration, and the pump capacity of the configuration D was 1.009 times the pump capacity of the comparative configuration. Therefore, it is considered that, if the starting angle is more than 2.5 degrees from the center angle on the upstream side in the rotation direction (the configuration A), the pump capacity is smaller than the pump capacity of the comparative configuration. This is due to the following reasons.

Although the discharge step is finished at the rotation angle at which the upstream-side vane passes through the downstream end of the discharge port, as the starting angle is positioned on the more upstream side in the rotation direction, the volume V of the pump chamber starts to increase at the rotation angle prior to finishing of the discharge step. Therefore, as the starting angle is positioned on the more upstream side in the rotation direction, the pressure in the pump chamber starts to decrease at the rotation angle prior to finishing of the discharge step; accordingly, oil that should be discharged during the discharge step is less likely to be discharged from the discharge port. As a result, as the starting angle is positioned on the more upstream side in the rotation direction, the pump capacity is reduced. Therefore, it is considered that, if the rotation angle difference of the starting angle from the center angle is larger than 2.5 degrees from the center angle on the upstream side in the rotation direction, the discharge flow rate becomes lower than the discharge flow rate of the comparative configuration.

From above, in the case where the starting angle is positioned on the upstream side of the center angle in the rotation direction, it is desirable that the rotation angle difference is 2.5 degrees or less.

The vane pump 1 related to the exemplary embodiment has 10 vanes 30. The ratio of the rotation angle difference 2.5 degrees to the rotation angle between the two vanes 30 constituting the pump chamber (hereinafter, referred to as the “rotation angle between the vanes” in some cases) is 2.5/(360/10)=0.07.

Therefore, the vane pump 1 related to the exemplary embodiment is characterized in that, in the case where the starting angle is positioned on the upstream side of the center angle in the rotation direction, the rotation angle difference is set at 0.07 x(360/10 (the number of vanes)) degrees or less.

First Modified Example

A vane pump 1 related to a first modified example is characterized in that the discharge side rotation angle difference between the starting angle and the rotation angle at the downstream end of the discharge port is not more than the suction side rotation angle difference between the starting angle and the rotation angle at the downstream end of the suction port. In other words, the vane pump 1 related to the first modified example is characterized in that the starting angle is the same as the center angle, which is the rotation angle at the center of the rotation angle at the downstream end of the discharge port and the rotation angle at the downstream end of the suction port, or the starting angle is on the upstream side of the center angle in the rotation direction.

However, it is preferable that the starting angle is on the upstream side of the center angle in the rotation direction, and on the downstream side of the position at the rotation angle difference of 2.5 degrees from the center angle in the rotation direction. Since the ratio of the rotation angle difference of 2.5 degrees to the rotation angle between the vanes is 0.07, it is preferable that the starting angle is on the upstream side of the center angle in the rotation direction, and on the downstream side of the position where the ratio to the rotation angle between the vanes of 0.07 in the rotation direction.

As shown in FIG. 13, assuming that the rotation angle of the center angle is 0 degrees and the upstream side direction in the rotation direction is negative, all the discharge flow rates of the configurations A, B, and C having the starting angles −2.5 degrees, −1.25 degrees, and 0 degrees, respectively, are 1.17 times or more the discharge flow rate of the comparative configuration. Therefore, the discharge side rotation angle difference between the starting angle and the rotation angle at the downstream end of the discharge port that is not more than the suction side rotation angle difference between the starting angle and the rotation angle at the downstream end of the suction port makes it possible to improve the pump efficiency as compared to the comparative configuration. In addition, it becomes possible to suppress the noise generated due to the backflow.

Second Modified Example

In the above-described exemplary embodiment, the highest points of the above-described convex portions drawn by the distances L of the respective rotation angles and the rotation angles providing the highest points are the same, the starting angles are different, and the amount of change in the distance L per unit rotation angle during the process to reach the rotation angle of the highest point from the starting angle is different. For example, the configurations A, B, C, D, and the comparative configuration are in the ascending order of the amount of change in the distance L per unit rotation angle (the inclination angle of the distance L in FIG. 6) during the process to reach the rotation angle of the highest point from the starting angle (refer to FIG. 12). However, if the capacity of the pump chamber in the vane pump 1 related to the exemplary embodiment starts to increase earlier than the capacity of the pump chamber in the comparative configuration, the vane pump 1 is not particularly limited to such an embodiment.

FIG. 16 is a diagram showing a part of the cam ring inner circumferential surface 42 related to a second modified example.

As shown in FIG. 16, the curvature radius R of the base end portion may be increased so that, of the rotation angle between the rotation angle providing the highest point of the convex portion drawn by the distances L and the starting angle, for example, about 80% is the same as the comparative configuration, and at a rotation angle of about 20% of the starting angle side, the distance L of the cam ring inner circumferential surface 42 related to the second modified example is larger than the distance L of the comparative configuration. Also in such a configuration, it is possible to start increasing the capacity of the pump chamber earlier than the comparative configuration, thereby making it possible to improve the pump efficiency, as well as making it possible to suppress the noise generated due to the backflow.

Note that FIG. 16 shows, as an example, the case in which the starting angle is the same as the center angle. As the starting angle is positioned on the more upstream side in the rotation direction, it is preferable to increase the curvature radius R.

REFERENCE SIGNS LIST

-   1 Vane pump -   2 First suction port -   3 Second suction port -   4 First discharge port -   5 Second discharge port -   10 Rotating shaft -   20 Rotor -   30 Vane -   40 Cam ring -   50 Inner plate -   60 Outer plate -   100 Housing -   110 Case -   120 Cover 

1. A vane pump device comprising: a rotor rotating while supporting 10 vanes to be movable in a rotation radius direction; and a cam ring having an inner circumferential surface facing an outer circumferential surface of the rotor, wherein a change in a distance from a rotation center of the rotor to the inner circumferential surface of the cam ring in response to a rotation angle of the rotor causes a change in a capacity of a pump chamber, which is partitioned by the outer circumferential surface of the rotor, the inner circumferential surface of the cam ring, and adjacent two of the 10 vanes, in response to the rotation angle, the change in the capacity of the pump chamber makes transition to at least a suction step in which working fluid is sucked into the pump chamber and a discharge step in which the working fluid is discharged from the pump chamber, a starting angle, which is a rotation angle at which the distance starts to increase after a segment with the same distance has reached a predetermined rotation angle, has a rotation angle difference of 2.5 degrees or less with respect to a center angle when the center angle is assumed to be an angle that equally divides the rotation angle at which a downstream-side end portion in a discharge port is formed and the rotation angle at which an upstream-side end portion in a suction port is formed, and, when it is assumed that a rotation angle of the center angle is 0 degrees, a downstream-side direction in a rotation direction is positive, and an upstream-side direction in the rotation direction is negative, the rotation angle at which the downstream-side end portion in the discharge port is formed is equal to or less than the rotation angle at which the segment with the same distance starts. 